The present invention relates to an assembly of a tubeless tire for heavy duty use and a wheel rim.
In conventional assemblies of a tire and a wheel rim, the bead portions of the tire are held upon the bead seats of the rim by means of air pressure in the tire and friction between the bead seats and the bead bottom faces. Accordingly, the bead portion is apt to move in the tire axial direction, if a lateral force acts on the tire when running deflated. If the bead portion is moved axially inwardly, the bead portion falls into a tire mounting well of the rim, and finally the tire is displaced from the rim.
As countermeasures to prevent tire displacement, there have been proposed:
a wheel rim provided with a protrusion located axially inside the bead seat to prevent axially inward movement of the bead portion;
a tire and wheel rim assembly in which the wheel rim is provided with a protrusion in the middle of the bead seat, the protrusion extending into a circumferential groove formed in the bead bottom of the tire (Japanese Patent Publication JP-A-49/13802); and
a tire and wheel rim assembly in which the tire is provided with a toe protruding radially inwardly into a circumferential groove formed axially inside the bead seat of the rim (PCT International Publication WO87/06889).
The assembly disclosed in PCT International Publication WO87/06889 is most effective in the prevention of tire displacement, but inferior in tire mounting and dismounting activities.
If the amount of protrusion of the toe and the groove depth are decreased, the mounting and dismounting becomes easy, but the engagement therebetween is also reduced, which results in easy displacement of the tire from the wheel rim.